The present invention generally relates to a system for decontaminating contact lenses. More particularly, the invention relates to a system with the use of which contaminants can be removed from and below the surface of contact lenses. Advantageously, the system includes an apparatus of a simplified construction by which a lens can be decontaminated efficiently.
A contact lens is a small, shell-shaped device having a dominant concave surface and a dominant convex surface meeting at a surrounding edge. In addition to being used generally to correct refractive errors of the eye on which the lens is placed, contact lenses may be worn also for cosmetic purposes.
Contact lenses can be made of a variety of materials. Glass is one type of such material. However, to provide a lens that does not easily crack, that is light, and that easily conforms to the cornea, groups of materials other than glass are now largely used to make contact lenses. Plastic materials, such as hydrogel plastics are one group of such materials widely used to make lenses. Hydrogel plastics have the unique property of being able to absorb and bind a proportionality large amount of water within a polymer network. A very flexible and soft structure results. Lenses made from hydrated hydrogel plastics are comfortable to wear because their softness allows them to easily conform to the cornea of the eye.
However, regardless of the material from which they are made, contact lenses are susceptible to contamination. A lens in place on the eye readily collects the oily and sebaceous substances and protein secreted by the eye. A lens positioned on the eye can collect also airborne chemicals and biological agents such as bacteria, viruses, and fungus. Furthermore, the simple handling of the lens by the user, such as during the placement of or the adjustment of the lens on the eye, can place a variety of foreign organic and inorganic substances on the lens.
Contaminants largely collect at the surface of lens. However, the hydrated polymer subsurface network of those lenses made from hydrogel plastics allow water-soluble substances and ions to readily enter and become lodged below the surface of these lenses.
The rate at which contaminants can accumulate on and in a lens is variable but generally rapid. It has been found that fifty percent of a lens surface may be covered by deposits after only a half-hour of lens wear. Within 8 hours, ninety percent of the lens surface may be coated. Complete coverage occurs typically within a matter of weeks. With time, new layers of contaminants form on the older layers of contaminants that were not removed by conventional cleaning methods. The contamination coating simply thickens.
Lens contaminants affect the optical performance of a lens. Sufficient layers of contaminants can accumulate on and within the lens to form a colored and/or partially opaque layer of oil, mucous, and crystalline deposits. The amount of light transmitted through the lens--and, therefore, visual acuity--diminishes depending on the composition, thickness, and extent of the contamination coating.
Lens contaminants affect also the mechanical performance of a lens. Lenses coated with a layer of contaminants can roughen the surface of a lens thereby transforming a smooth, easy-to-wear device to a roughened source of irritation. Rather than softly sitting on the cornea and allowing the eyelid to smoothly glide across its surface, the lens may cause abrasions and possible giant papillary conjunctivitis.
Sufficient amounts of contamination can ultimately affect the physiological compatibility of the lens with eye. The "tear exchange" and the oxygen exchange of the lenses with the eye may be decreased by increased amounts of foreign deposits on the lenses. A hydrogel lens that does not provide sufficient oxygen to the cornea can cause edema and corneal thickening. A coating of contaminants on a lens can also serve as an environment in which microorganisms, such as bacteria, fungi, and yeast, can flourish. Conditions such as conjunctivitis may result.
A variety of agents and techniques directed to the removal of lens contaminants are known. However, their usefulness is generally limited. Known agents and techniques are typically directed to the removal of only one or a few types of contaminants from the surface of a lens.
To illustrate this point, lenses are commonly cleaned with surfactants, oxidants, disinfectants, enzymatic cleaners, or abrasive, alone or in combination, and/or with the assistance of some additional cleaning technique and/or piece of apparatus. Surfactants are directed primarily to emulsifying and displacing more loosely bound layers of debris from the surface of the lens. Surfactant-based cleaners, however, cannot generally dislodge more tightly bound contaminants and/or those deposits that may have become denatured such as during an earlier cleaning attempts.
Oxidants are largely directed to disinfecting lenses, that is, the killing of any bacteria that can be reached by the oxidant. One form of oxidant is hydrogen peroxide. However, oxidants must be thoroughly removed from the lens before it is returned to the eye. Oxidants that come into contact with the cornea can cause stinging, tearing, photophobia, and, if in high enough concentrations or if allowed to maintain prolonged contact with the cornea, cellular damage.
Other disinfectants are known. However, many such chemical disinfectants can be absorbed by the lens and, if not removed prior to the placement of the lens back onto the eye, may also cause damage to it.
Enzymatic cleaners are used to remove the protein from lenses. Enzymatic cleaners utilize proteolytic-enzymes, such as papain, pancreatin, or subtilisin, to break up protein contaminants into water soluble pieces. Enzymatic cleaners are generally considered to be more effective than surfactant-based cleaners in accomplishing this specialized task. However, after lenses have been cleaned with these cleaners, they must be deactivated. Any enzymes remaining in the lens may attack the protein surface of the eye. Accordingly, enzymatic cleaning requires additional treatment steps, such as the application of hydrogen peroxide to the lens to deactivate the enzymes and then the removal of the hydrogen peroxide from the lens such as by rinsing.
Abrasives are directed to the removal of contaminants from the surface of the lens. Lens wearers typically work the abrasive manually over the surface of the lens until the wearer is satisfied that the lens is cleaned. Abrading away contaminants damaging the lens during the handling process, however, requires great physical dexterity on the part of the user. This is particularly true when the cleaning of lenses made from the softer plastic materials is attempted. Such lenses scratch easily. Furthermore, abrasive cleaning agents, as other cleaning agents, must be entirely removed from the lens before it is returned to the eye. Abrasive that are allowed to remain on the lens will cause abrasions and irritation to the cornea or eyelid.
Conventional cleaning agents are largely ineffective in removing all or even most of those contaminants which they are intended to remove. Because of this inefficiency, mechanical devices are often used in combination with the cleaning agents to improve their efficacy. Such mechanical devices vibrate, rotate, scrub, heat, agitate and/or direct ultrasonic waves to a lens in an attempt to further dislodge and/or deactivate the elements fouling the lens.
It has been estimated that, at a maximum, some fifty percent of the contaminants remain on the lens after the use of conventional cleaning agents and methods. Contaminants absorbed below the surface of the lens and within the polymer network of hydrogel lenses are largely unaffected by most of these techniques. In fact, some of the techniques actually exacerbate the contamination problem by denaturing the protein component of the contamination coating so that it forms an intractable layer. As a result, even by following recommended known cleaning procedures, the contamination layer gradually extends and thickens. Because of the increased irritation and the decreased visual acuity caused by this layer, lenses must eventually be discarded for new lenses. Typically, the replacement of lenses is required within one year.
A demand, therefore, exists for apparatus and methods by which a wide range of contaminants can be removed effectively and safely from contact lenses. The present invention satisfies the demand.
The present invention relies on the following principles and novel findings. Substances present in an aqueous environment, such as the contaminants deposited on and absorbed below the surface of a lens, have a surface electrical charge. Some contaminants have a positive surface charge while others have a negative surface charge. It has been found that by applying separate electrical charges to the lens these charged contaminants move to and/or off the surface of a lens and in a direction toward that charge that is opposite the charge which the contaminant has.
The present invention utilizes these principles and findings to decontaminate contact lens efficiently and safely. The novel apparatus of the present invention includes circuitry by which opposite charges can be produced on either side of a lens to electrokinetically draw contaminants from within and off of the lens.
Compared to some conventional cleaning agents, apparatus, and techniques, that kill or denature, but do not remove more than a limited percentage of contaminants from a lens, the present invention advantageously removes a large percentage of or all of the contaminants from a lens. Further, compared to other conventional cleaning, agents, apparatus, and techniques that generally kill, denature, and/or remove only certain of the contaminants present on the surface of the lens, the present invention further advantageously dislodges generally all of the contaminants from the surface of the lens. Additionally, compared to conventional cleaning agents, apparatus, and techniques that generally are unable to remove contaminants from below the surface of a lens, the present invention removes also these contaminants.
While contaminants removed by the use of conventional apparatus are allowed to freely come in contact with, and thereby possibly infect or contaminate the surfaces of the apparatus, the present invention includes novel means to prevent the dispersal of the lens contaminants. The present invention utilizes a protective encasement packet. The protective encasement packet is of a structure and is composed of a substance or substances such that the lens can be protected within it upon the lens' removal from the eye, through the cleaning process, and until the lens is readied for return to the eye. The protective encasement packet structure and composition facilitates the complete application of the electrical charges to the entire lens surface during the cleaning process. Contaminants removed from the lens during the cleaning stage are trapped and prevented from coming in contact with the surface of the apparatus. Advantageously, the need for post-procedure sterilization or extensive cleaning of the apparatus is obviated.
To clean a lens according to the present invention, the lens, upon its removal from the eye, is inserted within a protective encasement packet. The packet, within which the lens is safely encased, is positioned in a cleaning assembly according to the present invention. The cleaning assembly includes charge transmitting areas having surfaces that are positionable to either side of the lens within the packet. Opposite charges are produced in each of the charge transmitting areas. Contaminants at and below the surface of the lens are drawn toward the charge transmitting area having that charge that is opposite to the charge that the contaminant has. Those contaminants drawn off the lens surface are advantageously trapped within the protective encasement packet. In one preferred embodiment of the present invention, the protective encasement packet is made from a relatively inexpensive substance or substances such that the packet, and those contaminants trapped within it, may be discarded upon completion of the lens cleaning operation. Any contaminants dislodged to and at the surface of the lens can be easily removed from it, such as by rinsing.
Removal of generally all of the contaminants from a lens prevents the gradually increasing irritation of the eye caused by lenses that have been incompletely cleaned.
Removal of generally all of the contaminants from a lens is further advantageous in that it extends the life of a lens. Lenses cleaned with conventional cleaning agents and techniques must be discarded within a short period of time, such as a year, because of the increased irritation and decreasing visual acuity caused by the contamination build-up.
The present invention is advantageous also in that it is safe to the lens. Conventional cleaning agents and methods generally include one or more steps during which the possibility that the lens may be damaged is heightened. For example, one widely used technique in which an abrasive is used to clean a lens generally requires extensive handling of the lens during the entire cleaning operation. The lens may be harmed by mishandling and/or by the overzealous application of the abrasive to the lens surface.
Other conventional cleaning techniques require that the lens be placed into various containers or devices made of several pieces and/or having doors, covers, or lids that must be fitted, snapped, screwed, or closed shut. Often times these same containers are fitted into or form a part of an apparatus that rotates, spins, vibrates, heats, etc. the lens. The lens may be punctured, scratched, compressed, snipped, or otherwise damaged during the fitting, snapping, screwing, or closing shut of the lens container and/or during the prolonged exposure of the lens to conventional cleaning techniques.
Cleaning a lens with the present invention advantageously does not require the use of conventional containers and avoids the possibly dangerous prolonged unprotected exposure of the lens. The user simply removes the lens from his or her eye and inserts it into the protective encasement packet. The portion of the protective packet with which the lens may make contact during its insertion is generally soft and pliable so that the lens cannot thereby be scratched or damaged. As securely encased in the protective packet, the lens is positioned in the cleaning assembly. The charge transmitting areas are positioned to contact the packet such that opposing electrical charges are transmitted to the lens within the protective packet. Upon completion of the application of the electrical charges, the lens is still secured in the protective packet is withdrawn from the cleaning assembly. During the removal of the lens from the protective packet, soft and pliable substances within the protective packet may contact the lens. Accordingly, the possibility that the lens may be damaged during the cleaning procedure of the present invention is largely avoided.
Some conventional cleaning procedures may further require the consumer to coordinate the use of, for example, solutions, fluids, tablets, containers, and/or other complex, multiple component apparatus in what may be time-consuming procedures. Coordinating the use of many components and/or a complex apparatus is not a simple task especially by a consumer that has removed his or her lenses for cleaning.
The present invention provides advantageously an apparatus also of a simplified construction by which lenses can be cleaned simply, efficiently, and without the complicated procedures of known techniques. According to the present invention, the user places his or her lens in the protective encasement packet. The packet is easy to use even by those with temporarily limited vision caused by the removal of his or her lens. The packet is placed in the cleaning assembly. The lens, as encased in the protective packet, is subjected to electrical charges for a limited period of time. After the application of electrical charges, the packet is removed. The lens is removed from the packet and may be, after, for example, rinsing and soaking in saline solution, placed back onto the eye. Because the packet includes a substance that is in generally complete contact with the lens surface, the charges are applied to the entire lens surface. Accordingly, the lens is entirely cleaned and the partial cleaning or shadow effects of conventional apparatus and methods is avoided.
The present invention provides also apparatus and methods by which lenses may be cleaned inexpensively. Many conventional cleaning devices and techniques require the consumer to purchase once, or on an ongoing basis, solutions, fluids, tablets, containers, and/or other apparatus. In contrast, the present invention utilizes a cleaning housing and a protective encasement packet. The protective encasement packet may be made from components that may be reused. Additionally, the protective encasement packet may be made partially or entirely, from components that are generally inexpensive. Advantageously, a packet made from such materials may be discarded after a single use rather than cleaned and reused.
Additionally, the present invention does not require the great amount of time to set up and actually clean a lens as known apparatus and methods do. Compared to known apparatus and methods, lenses can be cleaned by the present invention in significantly less time and, generally, in minutes.
The present invention specifically overcomes the disadvantages of the conventional apparatus and methods that require also the coordinated use of fluid, containers for holding the fluid, containers in which lens or lenses must be retained so that the lens can be held under the surface of the body of fluid, and the application of electrical charges through the fluid and containers.
It is, accordingly, a general object of the present invention to provide apparatus and methods by which contaminants may be removed from contact lenses.
Another object of the present invention is to provide apparatus and methods by which contaminants may be removed from contact lenses safely and with minimal exposure and danger to the lens.
A further object of the present invention is to provide apparatus and methods by which contaminants may be removed from lenses simply and without the need to coordinate the use of multiple components in a complex cleaning procedure.
An additional object of the present invention is to provide apparatus and methods by which contaminants may be removed from contact lenses by the application of opposite electrical charges to the lens.
A further object of the present invention is to provide apparatus and methods by which contaminants may be removed from contact lenses and onto protective means to lessen the likelihood of exposure of the circuitry and the device in which it is held to the contaminants.
An added object of the present invention is to provide apparatus and methods by which contaminants may be removed quickly and generally in minutes.
These and other objects, features, and advantages of this invention will be clearly understood and explained with reference to the accompanying drawings and through a consideration of the following detailed description of the preferred embodiments.